There are demands for heat-resistant elastic materials in various fields such as adhesives, pressure-sensitive adhesives, sealing materials, heat dissipation, insulating, protective, and transfer sheets or films, greases, and coating films. In these application fields, there are various requirements concerning material hardness after solidification and surface properties. For example, sealing materials for LEDs are sometimes required to bond or adhere to a protective glass plate or a diffusion plate, or are sometimes required to have a tack-free release surface that does not adhere to a covering film used during transfer or for packing. Members for transferring flexible printed circuits (FPCs), called “heat-resistant carrier,” are required to have various levels of surface tack force depending on the types of FPCs to be transferred.
Such a demand for surface control may be satisfied not only by selecting the type of polymer as a base material but also by blending an inorganic filler into a base material having high tackiness to reduce and control tackiness. However, blending for developing tackiness generally tends to reduce heat resistance, and a tack-free material tends to be a hard material having high hardness. Addition of a filler also causes a problem with dispersibility or a reduction in adhesive force. Further, it is not technically easy to control surface properties in an environment in which a material is required to have heat resistance. As described above, a material having tackiness is generally poor in heat resistance, and addition of a filler for the purpose of controlling tackiness increases material hardness and reduces resistance to thermal shock.
Silicone resins have heretofore been used as heat-resistant materials. Silicone resins having low hardness and relatively high heat resistance have been practically used for a long time and variously improved. As a result, various developments have been made such as a reduction in cyclic siloxane component, an improvement in oil resistance, and an improvement in heat resistance that have been major issues. On the other hand, however, issues such as adhesiveness to a substrate or the like, electrical insulating properties, and gas barrier properties have not yet been resolved. This is because these many desired properties conflict with one another, and therefore it is difficult to achieve all the desired properties at the same time.
In order to develop these many desired properties, hybrid materials have been studied which utilize synergy between the properties of an organic component and the properties of an inorganic component. Particularly, many study results on and patents for phenyl-modified hybrids, which use, as raw materials, an alkoxide and a siloxane polymer mainly containing polydimethylsiloxane, have been reported by the present inventors etc. (Patent Literatures 1 to 4). These hybrids are greatly expected to be a breakthrough for electrical members or optical members due to the heat-resistant properties and flexibility of polydimethylsiloxane.